Vertical semiconductor device having semiconductor zones for improved operability under dynamic processes

Abstract

A vertical semiconductor device comprises a semiconductor body, a first contact and a second contact, wherein a first semiconductor region of a first conductivity type, a second semiconductor region of a second conductivity type and a third semiconductor region of a second conductivity type are formed in the semiconductor body in a direction from the first contact to the second contact, wherein a basic doping density of the second semiconductor region is smaller than a doping density of the third semiconductor region, and wherein in the second semiconductor region a semiconductor zone of the second conductivity type is arranged in which the doping density is increased relative to the basic doping density of the second semiconductor region.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims priority from German Patent Application No. 102005049506.0, which was filed on Oct. 13, 2005, and is incorporated herein by reference in its entirety.FIELD[0002]The present invention relates to a vertical semiconductor device, such as, for example, a diode, an IGBT or an MOSFET.BACKGROUND[0003]Vertical power semiconductor devices are increasingly used for switching high currents through loads, such as, for example, electric motors. Due to dynamic processes, such as, for example, overcurrent shutdown or short circuit loading, the result can be excessive field increases or too high an electric field in the power semiconductor device. Excessive field increases may result in large-area or filament-like or thread-like excessive current increases. When down-commuting the charge carriers from the space-charge region, for example, such an excessive field increase at or on the backside of the power semiconductor will result ...

AI Technical Summary

Benefits of technology

[0005]A vertical semiconductor device having improved electrical characteristics is disclosed herein.

[0006]In accordance with an embodiment of the present invention, a vertical semiconductor device is provided having: a semi-conductor body; a first contact on a first side of the semiconductor body; a second contact on a second side of the semiconductor body opposite the first side; wherein in the semiconductor body, in a direction from the first con-tact to the second contact, in the order mentioned, a first semiconductor region of a first conductivity type; a second semiconductor region of a second conductivity type; and a third semiconductor region of a second conductivity type are formed; wherein a basic doping density of the second semiconductor region is lower than a doping density of the third semiconductor region and the third semiconductor region is connected to the second contact in an electrically conductive manner; wherein in the second semiconductor region a semiconductor zone of the second conductivity type in which the doping density is increased relative to the basic doping density of the second semiconductor region is arranged such that it separates a first part of the second semiconductor region of the basic doping density arranged closer to the first semiconductor region from a second part of the second semiconductor region of the basic doping density arranged closer to the third semiconductor region; and wherein a maximum value of the doping density in the semi-conductor zone is in a range of greater than 1016 cm−3 and a thickness of the semiconductor zone along the direction from the first contact to the second contact is in a range of smaller than 3 μm.

[0007]In accordance with another embodiment of the present invention, a vertical semiconductor device is provided having; a semiconductor body; a first contact on a first side of the semi-conductor body; a second contact on a second side of the semiconductor body opposite the first side; wherein in the semiconductor body, in a direction from the first contact to the second contact, in the order mentioned, a first semiconductor region of a first conductivity type; a second semiconductor region of a second conductivity type; and a third semiconductor region of a first conductivity type are formed; wherein the third semiconductor region is connected to the second contact in an electrically conductive manner; wherein in the second semiconductor region a semiconductor zone of a second conductivity type in which the doping density is increased relative to the basic doping density of the second semiconductor region is arranged such that it separates a first part of the second semiconductor region of the basic doping density arranged closer to the first semiconductor region from a second part of the second semi-conductor region of the basic doping density arranged closer to the third semiconductor region; and wherein a maximum value of the doping densi

Problems solved by technology

Due to dynamic processes, such as, for example, overcurrent shutdown or short circuit loading, the result can be excessive field increases or too high an electric field in the power semiconductor device.

Excessive field increases may result in large-area or filament-like or thread-like excessive current increases.

When down-commuting the charge carriers from the space-charge region, for example, such an excessive field increase at or on the backside of the power semiconductor will result at the end of this process.

A probability of destroying the device here is the higher, the lower the basic doping of the starting material.

With a low basic doping of the starting material, only a low fixed space charge is available so that in dynamic processes, such as, for example, short circuit loading, down-commuting or overcurrent shut down, there is an increased probability of overcompensation of this space charge, which influences the distribution of the electric field in the power semiconductor negatively and may thus result in the device to be destroyed.

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